Has any one had this problem. 1987 350. So randomly the truck will get a little surge of power then the light will come on, sometimes it goes away after awhile, sometimes it doesn't. When I trip the light to blink it will just continuously blink or it will blink a 1 1 while driving. Truck seems like it's pretty gutless at times. Anything would be helpful.
CK5
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engine light issue
- Thread starter jrdtckr
- Start date
Trip the light to blink? You mean try to read the codes? You are only supposed to do this with the ign on, and truck NOT running. You can damage the computer by running it with the diagnostic port in code read mode .
http://www.obd-codes.com/faq/read-gm-2-digit-obd-codes-free.php
Short pins 1 and 2 with a paper clip, turn key to ON position (Don't start truck), and read flashes as described in that link.
Let us know what you find.
http://www.obd-codes.com/faq/read-gm-2-digit-obd-codes-free.php
Short pins 1 and 2 with a paper clip, turn key to ON position (Don't start truck), and read flashes as described in that link.
Let us know what you find.
So, when you read the codes with the truck off, what happens?
No codes?
Does it flash the code 12 as it is supposed to?
You may need an ECM.
No codes?
Does it flash the code 12 as it is supposed to?
You may need an ECM.
Well went threw the troubleshooting tree in the book and lead to saying that it's picking up a false knock on the wire the goes to the knock sensor. Wire had no resistance and I tried wrapping it in electrical tape as much as I could till it went in the conduit after that I'm lost again. Any ideas?
No resistance, as in short to ground?
If you unplug it from the knock sensor, then test, still short to ground?
If you unplug it from the knock sensor, then test, still short to ground?
chulisohombre
1/2 ton status
From what I read the knock Sensor sends a ground signal to the computer when it senses a knock. So it shouldn't have resistance at all unless it senses a knock in the engine. When it senses a knock it retards The Engine until the knock stops. Then it slowly lets the timing come back until it Knocks Again. That's how it keeps optimal timing and power without preignition in the engine. Mine was doing that when the fuel pump was going. Have you tested fuel pressure? Mine would surge then die out unless I have it 3/4 or more throttle once it
Got Bad enough. But it started Out as a lack of power. Then wouldn't idle right and was giving code 43 and some others. Everyone told me to check fuel
Pressure first before doing Anything else. Should be 9-15 lbs. and less
And it won't run right and start throwing codes.
Got Bad enough. But it started Out as a lack of power. Then wouldn't idle right and was giving code 43 and some others. Everyone told me to check fuel
Pressure first before doing Anything else. Should be 9-15 lbs. and less
And it won't run right and start throwing codes.
Have not checked fuel pressure, where an how would you check it at? The thing idls great and drives great on first start up. But once it gets about to operating temp I get a little surge of power then the light comes on then it feels real sluggish, I guess that's the retarded timing.
chulisohombre
1/2 ton status
I unscrewed the hard line from the back of the tbi. Then checked it from there. If its under 9 lbs then the fuel isn't squirting from the injectors correctly. At cold it dumps fuel constantly to help warm up engine. Mine ran ok when cold too. Once it warmed up it crapped completely.
If it were I, I'd just check pressure at the fuel filter. Both sides, to see drop across the filter. Need to remove a few of the clamps that hold the lines in place, but it's pretty easy to get to, and the fittings on the filter are pretty sturdy.
You in the UK? Any auto parts stores over there that "rent" testers for free? I've got one from Autozone right now, awaiting me putting the tank back in and checking that I solved all the pressure issues. I figure measuring across the filter is a good idea if like me you aren't interested in replacing it unless it's causing an issue.
You in the UK? Any auto parts stores over there that "rent" testers for free? I've got one from Autozone right now, awaiting me putting the tank back in and checking that I solved all the pressure issues. I figure measuring across the filter is a good idea if like me you aren't interested in replacing it unless it's causing an issue.
